S. Mech ¹, B. C. Das ¹, D. K. Sarmah ¹

Affiliations
1 Assam Agricultural University, Jorhat 785013, Assam, IN

Abstract

In the present investigation, carbendazim tolerance in Trichorderma harzianum was induced by exposing the culture to UV radiation for different periods (viz. 0, 2, 4, 6 and 8 h) and then the same were grown in PDA amended with different concentration of carbendazim viz. 0.01, 0.05, 0.1 and 1.0 per cent, respectively. In each concentration, colonies developed after 5 days were isolated, purified with serial dilution and sub-cultured thrice on PDA without carbendazim and tested their stability. These resulted in the development of 18 stable mutants, which could tolerate up to 0,1 per cent of carbendazim while wild T. harzianum (Th-w) failed to tolerate the same. Based on radial growth of above 18 stable mutants grown on fungicide free PDA, only three stable mutants were selected, which were designed as Th-M₁, Th-M₂ and Th-M₃, In vitro antagonistic activities of these three mutants tested against Sclerotinia sclerotiorum, the causal agent of white mold of French bean on PDA showed maximum reduction of radial growth of pathogen by Th-M₂ In another test, all the mutants arrested sclerotial production of S. sclerotiorum, significantly. However, the mutant Th-M₂ showed maximum reduction when it was inoculated seven days prior to inoculation with S. sclerotiorum in MSM (4%) as compared to wild T. harzianum (Th-w).

Keywords

Carbendazim, Mutant, Sclerotinia sclerotiorum, T. harzianum, UV Radiation, White Mold.

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